A study is being made of the effect of swimming exercise on lipid peroxidation in rats. Pentane, which derives from omega 6-fatty acid hydroperoxides, is being measured in respiratory gas as an index of in vivo lipid peroxidation. Another study underway is attempting to correlate respiratory carbonyl products of lipid peroxidation with hydrocarbon gas products, mainly ethane and pentane. For this study comparisons will be made on vitamin E-deficient rats, iron-dextran-injected rats, and halomethane-injected rats. The acute toxic effects of a number of compounds that induce lipid peroxidation will be assessed by the measurement of respiratory hydrocarbon gases. These compounds include phenylhydrazine, vitamins A and K, hydrogen peroxide, lipid hydroperoxides, and alpha-benzopyrene. In vitro studies on the fluorescent products that develop upon crosslinking of malonaldehyde with DNA will be made. The crosslinking of DNA and proteins and of DNA with DNA will also be made. Studies on the nature of the fluorescent products in elastin have been underway for some time. Completion of work on identification of the major fluorescent components should be achieved this year. This study is being done in order to determine from structure whether the fluorescent compounds arise via natural occurrence or from a lipid peroxidative damage mechanism.